Piston pump lubrication structure



Feb. 21, 1967 H. R. ORTH 3,304,885

PISTON PUMP LUBRICATION STRUCTURE Filed April 50, 1965 4 Sheets-Sheet 1Iifi U 1 M M 57 95- m T R 3 2 INVEN 0 HAROLD R. ORTH ATT'Y.

Feb. 21, 1967 H. R. ORTH 3,304,885

PISTON PUMP LUBRICATION STRUCTURE Filed April 50, 1965 4 Sheets-Sheet {5INVENTOR HAROLD R. ORTH BY 71 P. X

ATT'Y.

' j 7 H. R. ORTH 3,304,885

PISTON PUMP LUBRICATION STRUCTURE Filed April 50, 1965 4 Sheets-Sheet 4HA ROLD R. ORTH United States Patent 3 304 885 PISTON PUMP LUQRIXEATIONSTRUCTURE Harold R. Orth, La Grange, IlL, assignor to InternationalHarvester Company, Chicago, III., a corporation of New Jersey Filed Apr.30, 1965, Ser. No. 452,090 6 Claims. (Cl. 103-162) This inventionrelates generally to variable displacement axial piston pumps andmotors; and more particularly relates to axial piston pumps and motorshaving improved lubricating structures.

As is well known, when an axial piston pump is driven mechanically, itfunctions as a pump to pump a working fluid from a low pressure sourceinto a high pressure outlet line; and when it is supplied with arelatively high pressure flow of fluid, the pump functions as a motor tosupply a mechanical output of power. Consequently, while for purposes ofsimplification the invention will be referred to as a pump in thedescription and claims which follows, it should be clear that theinvention may be employed with equal advantages when the invention isfunctioning as a motor.

In the usual case, axial piston pumps have been cooled and lubricated bysubmersion in a wet sump or fluid reservoir containing a fluid suitablefor lubrication and cooling of the components of the pump.Unfortunately, such submersion results in considerable churning of thefluid increasing its operating temperature and decreasing pumpetficiency. Increased fluid operating temperatures leads to pumpoverheating and maximum pump operating speed is limited severely withsubmerged lubrication.

Other axial piston pumps are lubricated by an external spray method toavoid power losses and overheating caused by oil churning. While theexternal spray lubrication method avoids the churning losses ofsubmerged lubricataion, pump operating speeds are still severely limitedby maximum safe operating temperatures; while the lubricant sprayed onthe pump cools its external surfaces to some extent, some pumpcomponents are relatively inaccessible to the lubricating spray. Thusthe rotating pump shaft is relatively inaccessible to external spraylubrication and must rely upon somewhat inadequate chance lubrication toprevent shaft wear and fretting, as in its splined drive areas, due toshaft deflection. Also, at high speeds contemplated of over 3000 r.p.m.with conventional lubricating methods such as external spray lubricationor submerged lubrication, pump overheating inevitably occurs due tocentrifugal forces which tend to throw. lubricating fluid supplied tothe pump centrifugally outwardly, keeping the lubricating fluid awayfrom the internal components of the pump.

In hydrostatic transmissions incorporating two of the devices hereincontemplated functioning individually as an axial piston pump and-as anaxial piston motor coaxially arranged, power losses are considered verycritically, and as would be expected, ways to avoid reductions inefficiency due to friction or overheating are constantly sought.Friction of the pump and motor valve plates rubbing together inoperation of the transmission without sufficient cooling and lubricationtends to result in pump overheating and destruction of the valve plates.With relatively larger transmission units utilizing relatively largervalve plates having relatively larger rubbing surfaces, safe operatingspeeds are further limited. Additionally, pump and motor slippers andthrust plates have a rather limited operating life at high speeds andtend to become unserviceable after only a few hundred hours ofoperation, due to overheating and oxidizing of lubricant.

Thus, an object of the invention is to provide an improved axial pistonpump.

Another object of the invention is to provide an axial piston pumphaving an improved lubrication structure to permit operation at higherspeeds.

Still another object of the invention is to provide a simple relativelyfoolproof axial piston pump arrangement to achieve forced lubricationand cooling of the pump components.

Still another object of the invention is to provide an improved axialpiston pump lubricating system to achieve selective lubrication ofinternally disposed pump compo nents such as pump shaft bearings, valveplates, and shaft splines as well as relatively inaccessible internalsurfaces of pump slippers, slipper retaining guides and thrust plate.

Yet another object of the invention is to provide an improved axialpiston pump structure to achieve internal lubrication of the pumpcomponents to permit safe operation of the pump at relatively highoperating speeds of over about 3000 r.p.m.

A further object of the invention is to provide a lubricating system foran axial piston pump operating in a dry sump where pump components arenot picking up lubricating fluid by rotation within a fluid, and toachieve lubrication of the pump without churning power losses associatedwith submerged pump operation.

Sill another object of the invention is to provide a forced lubricatingsystem for a hydrostatic transmission incorporating an axial piston pumpand an axial piston motor coaxially arranged and cooperating fooperation at high speeds of over about 3000 r.p.m., the lubricatingsystem directing a central flow of lubricating and cooling fluid tointernal components of the pump and motor.

These and other objects of the invention will become clear from thefollowing description taken in conjunction with the appended claims anddrawings, wherein:

FIG. 1 is,a somewhat schematic, simplified sectional view of anembodiment of an axial piston pump constructed in accordance with thepresent invention;

FIG. 2 is a somewhat schematic, sectional view of a hydrostatictransmission including an axial piston pump and an axial piston motorboth constructed in accordance with the teachings of the presentinvention;

FIG. 3 is a somewhat schematic simplified sectional view similar to FIG.1 of another embodiment of an axial piston pump constructed inaccordance with the invention;

FIG. 4 is a schematic representation of a flow diagram of an axialpiston pump as illustrated in FIGS. 1' and 3;

FIG. 5 is a schematic representation of a flow diagram of a hydrostatictransmission as illustrated in FIG. 2;

FIGS. 6 and 7 are end sectional views taken along the lines 66 and 7-7respectively of FIG. 1;

FIG. 8 is an enlarged sectional view taken along the 0 line 88 of FIG. 6showing a valve plate portion of the axial piston pump of FIG. 1;

FIGS. 9 and 10 are end sectional views taken along the lines 99 and10-10 respectively of FIG. 3;

FIG. 11 is an enlarged sectional view taken along the line 11-11 of FIG.9;

FIG. 12 is an enlarged somewhat schematic sectional view of anotherembodiment of an axial piston pump similar to the showings of FIGS. 8and 11 but constructed without valve plates;

FIGS. 13 and 14 are end sectional views taken along the lines 1313 and14-14 respectively of FIG. 12.

Referring to the drawings, FIG. 1 shows an axial piston pump 10including a rotatable cylinder block 12 having a plurality of axiallyextending splines, the block being splined on a rotatable drive shaft 14driven by an associated source of power such as a vehicle engine 15,FIG. 4, the shaft 14 having a plurality of axially extending splines 16complementary to the cylinder block splines for rotation of the cylinderblock with the drive shaft 14;

The cylinder block 12 has a plurality of axial cylinder bores 18therein, each housing one of a plurality of reciprocable pistons 20,each of the pistons 20 having a ball or outer end 22 force fitted withinindividual sockets 23 provided for this purpose in a pump sockctedbearing surface or slipper 24. First and second valve plates 32, 28respectively are provided for receipt or exhaust of a fluid from thecylinder bores 18. The cylinder block 12 is biased by .a cylinder blockspring 26 against the second or right valve plate 28 pinned to orintegral with the cylinder block 12 for rotation therewith. The valveplate 28 comprises a bearing plate which may be but is not necessarilyintegral with the block 12 having a flat valving surface 30. Plate 28rotates with respect to the first Valve plate or port plate 32 having aflat complementary valving surface 34 which bears or slides against thefiat face 38 of the right valve plate 28. The first valve plate 32 ispinned to a housing 36, although it may be integral with the housing 36,a portion of which is shown in the drawing, and is thus maintainedstationary. The first and second valve plates 32, 28 are formed withcomplementary arcuate shaped ports 40, 38 for successive fluidcommunication with ports 42 in the cylinder bores 18 as the cylinderblock 12 rotates to admit and exhaust a working fluid, not shown, to andfrom the cylinder bores 18, as is well known in the art.

The ball ends 22 of the pistons 28 cooperate with a swash plate assemblyincludin a swash plate 44 pivotable about the drive shaft 14 by means ofa pair of trunnions 46, 48 having a plurality of trunnion bearings 50comprising tapered roller bearings supporting the swash plate 44. As iswell understood, the swash plate 44 is pivoted between a minimumdisplacement neutral position approximateiy as shown in FIG. 1 tomaximum displacement positions, as shown generally in FIG. 2, atopposite sides of the center position in order to vary the fluiddisplacement of the pump. The pump drive shaft 14 is connected forrotation with an input shaft, not shown, to rotate the drive shaft.

The swash plate 44 has a generally cylindrical inner portion 54 with anannular thrust plate 56 therein providing a flat bearing surface 57 forthe slipper 24 which slides thereon. A slipper retainer 58 and slipperretainer guide 60 are provided to maintain the slipper in bearingposition against the thrust plate 56, the slipper retainer guide 60being biased to the right, as viewed in the figure, by a slipperretainer spring 62. The slipper retainer guide 60 is splined to theshaft 14 for rotation therewith and has a generally spherical outersurface 64 on which a complementally spherically shaped inner surface 66of the slipper retainer 58 slides.

First and second main shaft bearings 68, 70 are positioned at the leftand right ends of the main shaft to support the shaft 14 for rotationwithin the pump housing 36.

In accordance with an important feature of the invention, the rotatablemain shaft 14 is provided with an axially extending central passageway74 in communication with a plurality of first, second and third radialpassageways or openings 76, 78, 80 in communication therewith forreceipt of a lubricating fluid. The first radial passageways 76 arecomm-unicatively connected to the first main shaft bearing 68 which isin communication with a plurality of radially extending passageways 84,82 provided respectively in the first and second valve plates 32, 28 tocarry a lubricating fluid radially about the valve plates to dissipatethe heat generated by the intermediate rubbing surfaces 34, 30 of thevalve plates.

The splined area of the pump shaft 14, extending axially from anintermediate portion 86 of the shaft toward the right end of the shaftadjacent the pump slippers 24, is subject to considerable wear andfretting due to rotational deflection. In accordance with the invention,the splines 16 of the shaft and the splines, not shown, of the cylinderblock 12 are slightly undercut to provide undercut spline passagewaysdesignated by the numeral 85 for the flow of lubricating fluid. Thesecond or intermediate radial passageways 78 are positioned immediatelyadjacent the spline-d area at the left or valve plate end of the splines16 and are in communication with the undercut passageways 85 provided inthe splined area. The right hand end of the cylinder block is notched atpoints indicated by the numeral 86 and a plurality of radial openings 87in line therewith are provided in the slipper retainer guide 60, theopenings 87 being in communication with the intermediate radialpassageways 78 by means of the undercut spline passageways 85 forreceipt of lubricating fluid therefrom.

The third radial passageways 86 are positioned at the right end of theaxially extending central passageway 74 at the right hand end of thepump shaft 14 leading to and being in communication with the right shaftbearing 70 to direct a flow of lubricating fluid through the hearing.

The annular thrust plate 56 has an inner edge 90 adjacent the slipperretainer guide 60 which edge 98 is chamfered so as to encourage the flowof lubricating fluid flowing radially outwardly from the openings 85, 87to flow over surface 57 rather than through opening 89. Having nowdescribed the invention, its operation should be clear; however, forpurposes of a better understanding of the invention, the manner in whichthe axial piston pump is lubricated and coo-led will be explained.

Conventional means 180, FIG. 4, are provided to direct a flow oflubricating fluid under pressure from a reservoir 182 to the pump 10 atthe left end of the axially extending central assageway 74 in the pumpshaft 14, with arrows indicating the direction of flow. Fluid enters thepump at the valve plate area and travels axially to the right throughthe passageway 74 entering the first, second and third radialpassageways 76, 78 and 80. Lubricating fluid first enters radialpassageway 76 flowing through and lubricating the main shaft bearings 68and then flowing radially outwardly through the valve plate passageways82, 84 to cool the valve plates, the fluid then being directed byconventional means, not shown, to a fluid reservoir 182, FIG. 4.

Another portion of the flow of fluid from the axial passageway 74 flowsradially outwardly through passageways 78, to the right through theundercut spline passageways 85 where the flow of fluid lubricates andcools the splined area of the shaft which is highly stressed due toflexure of the shaft with a consequent tendency to wear out. Thelubricating fluid continues through notches 86 provided in the right endof the cylinder block 12 in communication with openings 87 provided inthe slipper retainer guide 60 where the chamfered thrust plate 56encourages the lubricating fluid to flow over the chamfered edge of thethrust plate rather than through an opening 89 provided in the thrustplate 56. The lubricating fluid from the intermediate radial passageways78 then sprays centrifugally outwardly from the slipper retainer guideopenings 87 to lubricate and cool the surfaces of the slipper retainerguide 60, slipper 24 and slipper retainer 58; and the fluid continues ina spray radially outwardly through openings, not shown, provided in theswash plate 44 to lubricate the trunnion bearings 50, as indicated bythe arrows, before returning to the fluid reservoir 182, FIG. 4.

The third radial passageway 80 in fluid communication with the rightshaft bearings 70 permits flow of lubricating fluid from axialpassageway 74 through the right shaft bearings 70 with means, not shown,provided in the pump housing for return of the lubricating fluid to thefluid reservoir 182, FIG. 4.

The manner in which the first and second valve plates 32, 28 areconstructed may best be seen by reference to FIGS. 6 to 8 shown inconjunction with an axial piston pump similar to that illustrated inFIG. 1 but utilizing conventional straight roller bearings 68b insteadof the tapered roller bearings 68 utilized in the embodiment of FIG. 1.The second valve plate 28, FIG. 7, has

arcuate shaped ports 38, forming no part of the present invention, andhas'an inner annular ring 198 and an outer annular ring 200 straddlingthe ports 38, the rings 198, 200 being connected communicatively byradial passageways 82 with inner and outer radial passageways 202, 204respectively, passageways 202 communicatively connecting the inner ring198 to the area about the first main shaft bearing 68 and passageways204 carrying lubricating fluid radially outwardly from the outer ring200 to the peripheral edge of the valve plate 28 and thence to thereservoir.

The first valve plate 32, FIG. 6, constructed in a similar manner tovalve plate 28, has an inner ring or annular fluid channel 190 and anouter ring or annular fluid channel 192 straddling ports 40 and beingcommunicatively connected by radially extending passageways 84, withinner radial passageways 194 provided to connect the inner ring 190communicatively with fluid from the fluid area about the first mainshaft bearing, with outer radial passageways 196 provided to connectcommunicatively the outer ring 192 to the peripheral edges of the firstvalve plate 32 and thence to reservoir.

Another embodiment of the invention is illustrated in FIG. 3 and FIGS.9-11 wherein like parts are designated by like numerals with theaddition of the sufiix a for identification. Since the basic structureshown in FIG. 3 is a conventional axial piston pump similar to the axialpiston pump of FIG. 1 and designated generally by the numeral 10a, anadditional description of such similar conventional features will not begiven. Rather, those features, wherein the pump of FIG. 3 differs fromthe pump of FIG. 1 and which features embody the concepts of the presentinvention, will be described.

The axial piston pump 10:: includes a housing 36a having a passageway190 which is in fluid communication with a source 180a of lubricatingfluid under pressure. An antifriction bearing 68a supporting one end ofpump shaft 14a is in communication with radial fluid passageways 212,84a provided in valve plates 28a and 32a; and the bearing 68a is also influid communication with a fluid chamber 192 provided about spring 26a.The chamher 192 is in fluid communication with undercut splinedpassageways 85a provided about the splined area 16 of the shaft by meansof a passageway 194 in the housing about shaft 14.

The right hand end of cylinder block 12a is notched at points indicatedby the numeral 86a and a plurality of radial openings 87a in linetherewith are provided in the slipper retainer guide 60a, the openings87a being in communication with the undercut splined passageways 85a forreceipt of lubricating fluid therefrom. Annular thrust plate 56a has aninner edge 90a adjacent the slipper retainer guide 60a which edge 90a ischamfered so as to direct the flow of lubricating fluid radiallyoutwardly from opening 86a, 87a in the slipper retainer guide 60a toflow over surface 57a of thrust plate 56a rather than through opening89a, the openings 87a being in communication with the undercut splinedpassageways for receipt of lubricating fluid. The manner of operation ofthe lubricating structure of the axial piston pump V embodiment shown inFIGURE 3 will now be described. Conventional means 180a are provided todirect the flow of lubricating fluid under pressure from a source 182aof lubricating fluid to the axial piston pump 10a,

lubricating fluid moving through opening 190 at the left end of housing36a with arrows indicating the direction of flow. Fluid then enters theanti-friction bearings 68:: where a portion of the flow moves radiallyoutwardly through the valve plate passageways 82a, 84a to cool the valveplates, the fluid then being directed by conventional means, not shown,to the fluid reservoir.

Another portion of the flow of fluid from the bearings 68a moves axiallyto the right, as viewed in the figure into the fluid chamber 192 aboutspring 26a, way 194 about the shaft 14a, continuing into passageto theright through the undercut splined passageways a where the flow of fluidlubricates and cools the splined area of the shaft. The lubricatingfluid continues through notches 86a in the right end of the cylinderblock 12a in communication with openings 87a in the slipper retainerguide where the chamferedthrust plate 56a encourages the lubricatingfluid to flow over the chamfered edge of the thrust plate rather thanthrough opening 89a provided in the swash plate 56a. The lubricatingfluid then sprays centrifugally outwardly from the slipper retainerguide openings 87a to lubricate and cool the surfaces of the slipperretainer guide 60a, slipper 24a and slipper retainer 58a; and the fluidcontinues to spray radially outwardly through openings, not shown, inthe swash plate 44a, to lubricate trunnion bearings 50a, the fluid thenbeing directed by conventional means, not shown, to the fluid reservoir.

The manner of construction of the valve plate and cylinder block valvingsurface of the embodiment of the axial piston pump illustrated in FIG. 3is best seen by reference to FIGS. 9-11. A first valve plate or portplate 32a is illustrated in FIG. 9 pinned to the housing 36a, the platebeing similar in construction to valve plate 32, FIG. 6, including innerand outer rings 190a, 192a, inner and outer radial passageways 194a,196a and intermediate radially extending passageways 84a communicativelyconnecting the inner and outer rings 190a, 192a. Thus, fluid is directedradially outwardly from about the first main bearing 68a to radialpassageways 194a, inner ring 190a radially extending passageways 84a and212, FIG. 10, to the outer ring 192a and via outer radial passageways196a to the reservoir.

The cylinder barrel 12a, FIG. 11, is provided with a valving surface 205which is complementary to the flat valve face of valve plate 320.Cylinder barrel 12a has complementary inner and outer rings 206, 208 andarcuate ports 38a similar to the ports of the second valve thoseutilized in FIGS. 9-11 with the addition of the suffix c foridentification. The axial piston pump, designated generally by thenumeral 100, with only a portion of the pump being illustrated, includesa cylinder block 12c and a housing or end cap 360, FIG. 13. End cap 360has arcuate shaped ports 40c therein and has a valving surface,designated generally by the'numeral 214 which is complementary to a flatvalving surface 216 of the cylinder barrel 12c. The cylinder barrel 120,FIG. 14, is provided with arcuate ports 38c, inner and outer rings 206e,208a, inner radial passageways 210e, radially extending passageways212e, and outer radial passageways 217 communicatively connecting theinner ring 206c to the outer ring 2080 and thence to the outer peripheryof the cylinder barrel and to a reservoir, not shown.

Referring now to FIG. 2, a hydrostatic transmission designated generallyby the numeral 92 is shown having an axial piston pump 96 and an axialpiston motor 98 coaxially arranged with a transmission housing, notshown, with a common central stationary section 100 ing pump and motorvalve plates 109, 111 pinned to opposite sides thereof, the centralsection'100 being stationarily mounted within the transmission housing.The respective pump and motor cylinder blocks 101, 103 of the pump andmotor 96, 98 are biased by springs, not

The pump and motor second valve plates 102, 104 and central sechav-'motor cylintion 100 with its first valve plates 109, 111 are formed withcomplementary cooperating arcuate shaped inlet and outlet portsindicated respectively by the numerals 106, 108 in the pump and motorsecond valve plates 102, 104 and by the numerals 110, 113, 115 in thecenter section 100 and pump and motor first valve plates 109, 111respectively for successive communication with ports 112, 114 incylinders 116, 118 of the pump and motor cylinder blocks 101, 103.

Outer ball ends 120, 121 of pistons 122, 123 in the pump and motorrespectively cooperate with swash plate assemblies 124, 126 similar tothe assembly illustrated in FIG. 1 and including pump and motor swashplates 128, 130, pump and motor thrust plates 132, 134, pump and motorslippers 136, 138, pump and motor slipper retainers 140, 142 and pumpand motor slipper retainer guides 144, 146. Ball ends of the pump andmotor pistons 122, 123 cooperate with the swash plates 128, 130 whichare pivotable in opposite directions from a minimum displacement neutralcenter position such as illustrated in FIG. 1 to a maximum displacementposition with the swash plate 128, 130 generally as illustrated in FIG.2 in order to vary the displacement of the pump, as is well understoodin the art. A pump drive shaft 140 is connected for rotation with aninput shaft, not shown, adapted to be driven by a prime mover such as aninternal combustion engine 41, FIG. 5, conventionally associated withtractors and the like.

The motor 98 is identical in construction to the pump 96 but may besomewhat larger than the pump 96 as indicated generally in FIG. 5, withthe motors cylinder block 103 .splined on an output shaft 142 forrotation therewith. The arcuate ports 108 and 115 of the motor valveplates 104 and 111 cooperate with ports 110 of the center section 100and the valve plate ports 113 and 106 of the pump valve plates 102 and109 so that the pump and motor are connected in a closed, closely coupled hydraulic circuit.

Ball ends 121 of the motor pistons cooperate with the motor swash plateassembly 126 which is variable between a minimum allowable displacementposition as illustrated in FIG. 1 and a maximum displacement position asillustrated in FIG. 2. The motor shaft 142 is connected to an outputshaft, not shown, adapted to be connected to the propelling wheels of anassociated vehicle such as a tractor. The swash plate assemblies 124,126 are controlled by means, not shown, such as by hydraulicallyactuatable piston assemblies, as is well known in the art.

The pump and motor shafts 140, 142, respectively, are each provided witha central axially extending lubricant passageway 144, 146 respectivelywith first, second and third radially extending pump passageways 148,150, 152 in communication with axial pump passageway 144 andcorresponding to first, second and third radial passageways 76, 78, 80as illustrated in FIG. 1. First, second and third radially extendingmotor passageways 154, 156, 158 in communication with the axiallyextending center motor passageway 146 are also provided. Additionalpassageways for flow of lubricating fluid are provided in the pump 96and motor 98 similar to those provided in the pump, FIG. 1, includingpump and motor splines 160, 162 which are slightly undercut providingundercut spline passageways in communication with the second orintermediate radial passageways 150, 156 and leading communicatively tocylinder block notches, not shown, and slipper retainer guide openings164, 166 providing lubrication respectively for the pump and motorthrust plates, slippers, slipper retainers, and slipper retainer guides.The pump and motor radial passageways 148, 150, 152 and 154, 156, 158provide lubrication for pump and motor main shaft bearings 168, 170 andother bearings, not shown, supporting the shaft for rotation and furtherprovide coolant for the pump and motor second valve plates 102 and 104,first valve plates 109 and 111 and 3 center section by means of radiallyextending tanking grooves or passageways provided in the valve plates,being in communication with shaft bearings 168, 170.

Conventional means 184, FIG. 5, provide a flow of lubricating fluidunder pressure to the axial shaft passageways 144, 146 as by a radialopening 172 in the center section 100 in communication with the pump andmotor axial passageways 144, 146 thus providing a central common fiow oflubricant and ensuring selective forced lubrication and cooling of thevarious wearing surfaces of the pump and motor to permit safe andefficient operation of the hydrostatic transmission at high speeds ofover about 3000 to 4000 r.p.m.

Since modifications of the details of the structures as illustrated inthe figures are contemplated, the invention should be limited only bythe scope of the appended claims.

The invention is claimed as follows:

1. In an axial piston pump including a housing, a rotatable drive shaftextending through said housing, said shaft having first and second ends,first and second antifriction bearings supporting said shaft at itsfirst and second ends respectively for rotation within said housing,said shaft having an outer area having a plurality of splines extendingaxially from a first point at an intermediate location on said shaft andextending to a second point adjacent the second end of said shaft, acylinder block having first and second spaced ends and a plurality ofaxially extending splines being complementally positioned to the splineson said shaft for rotation therewith, said cylinder block having aplurality of axial cylinder bores, a plurality of pistons, each of saidbores housing one of said pistons for reciprocation therein, saidpistons each having a ball portion at one end thereof, said ballportions extending outwardly from said cylinder bores toward the secondend of said shaft and being fitted within socketed bearing surfaces, aswash plate assembly being positioned about the shaft at its second endadjacent the socketed bearing surfaces, said bearing surfaces beingpositioned within said swash plate assembly for controlled reciprocationof said pistons, said housing and said cylinder block havingrespectively first and second complementary relatively rotatable annularvalve plates to control the flow of fluid through said piston pump, saidvalve plates being positioned adjacent said first anti-frictionbearings, said first and second valve plates having mating relativelyrotating complementary face portions the improvement comprising:

means providing at least one of said first and second valve plates withradially extending fluid passageways therethrough; said passagewaysbeing adjacent said face portions,

means providing an axial shaft passageway extending axially through saidrotating shaft between said first and second anti-friction bearings;

means providing said shaft with first radially extending passagewayspositioned adjacent said first antifriction bearings and extendingcommunicatively between said axial shaft passageway and said firstantifriction bearings;

means communicatively connecting said first anti-friction bearings andsaid radially extending valve plate passageways;

means providing said shaft with second radially extending passagewayspositioned adjacent said splined area of said shaft between said firstend of said shaft and said intermediate location on said shaft,

means providing splined fluid passageways extending axially between saidsplined area of said shaft and said cylinder block, said splined fluidpassageways communicatively connecting said second radially extendingshaft passageways with said swash plate assembly;

and means providing a source of lubricating fluid under pressure to saidaxially extending shaft passageway,

whereby lubricating fluid under pressure is directed in a lubricatingand cooling stream through said first antifriction bearings, said valveplates, about the splined area of said shaft and said swash plateassembly.

2. An axial piston pump to be operated at high speeds in a dry sump,comprising a housing; a rotating drive shaft extending through saidhousing, said shaft having first and second ends; first and secondanti-friction bearings mounted in said housing supporting said shaft atits first and second ends respectively for rotation within said housing,said shaft having an outer area having a plurality of axially extendingsplines extending from a first point intermediate said first and secondends of said shaft and extending to a second point adjacent said secondend of said shaft; a cylinder block splined to said shaft for rotationtherewith having first and second spaced ends and a plurality of axiallyextending splines complemental in shape to said shaft splines andpositioned for engagement with said shaft splines, said cylinder blockhaving a plurality of axial cylinder bores; a plurality of reciprocablepistons housed individually within said bores, said pistons each havinga ball portion at one end thereof extending outwardly from said cylinderbores toward a plane perpendicular to the second end of said shaft; aswash plate assembly pivotable about the second end of said shaft andpositioned adjacent the ball portions of said pistons to control theaxial reciprocation of said pistons, said swash plate assembly includinga swash plate being pivotable about the shaft, pivoting means forpivoting said swash plate about said shaft and including a plurality oftrunnion bearings supporting the swash plate, a pump slipper having aplurality of sockets f-orce fitted about the ball portions of saidpistons to maintain said pistons within their respective bores, anannular thrust plate providing a bearing surface for said slipper, aslipper retainer guide splined to said shaft for rotation therewith andhaving a generally spherical radially outer surface, a slipper retainerto maintain the slipper in bearing position against the thrust plate,said slipper retainer being fitted about said slipper and having agenerally spherical shaped radially inner surface of said slipperretainer guide for sliding movement thereon;

said pump housing and said cylinder block respectively having first andsecond annular valve plates positioned about said shaft between saidhousing and said first end of said cylinder block adjacent said firstanti-friction bearings, said first and second valve plates each havingcomplemental relatively rotating bearing surfaces, said valve plateseach having a plurality of axially extending cooperating pump portstherein for fluid communication with complementary ports provided insaid cylinder block bores, means providing said valve plates with aplurality of radially extending fluid passagewaysin communication withsaid first anti-friction bearings;

means providing an axially extending passageway through said shaftincluding means providing an inlet opening for receipt of a lubricatingfluid under pressure;

a reservoir for lubricating fluid;

means providing a source of lubricating fluid under pressure to saidinlet opening;

means providing first radially extending shaft passagewayscommunicatively connecting said axially extending shaft passageway tosaid first anti-friction bearings;

means communicatively connecting said first anti-friction bearings andsaid radially extending valve plate passageways;

means providing splined fluid passageways in said splined area of saidshaft in fluid communication with said cylinder block;

a plurality of notched passageways in said cylinder block adjacent saidshaft splines being in fluid communication with said axially extendingsplined fluid passageways;

means providing a plurality of openings in said slipper retainer guide,said openings being in communication with said notched passageways insaid cylinder block for receipt of fluid under pressure from saidsplined fluid passageways;

means providing second radially extending passageways at an intermediateportion of said shaft immediately adjacent said splined area of saidshaft between said first end of said shaft and said splined area, saidsecond radially extending passageways communicatively connecting saidaxially extending shaft passageway and said splined fluid passageways;

and means providing third radially extending fluid passageways in saidshaft communicatively connecting said axially extending shaft passagewayto said secone anti-friction bearings;

whereby lubricating fluid under pressure is directed a rotatable driveshaft extending through said housing, a lubricant reservoir, first andsecond anti-friction bearings supporting said shaft at its first andsecond ends respectively for rotation within said housing,

means for rotating said shaft, said shaft having a splined outer areahaving a plurality of axially extending splines extending from anintermediate location on said shaft toward a point adajcent the secondend of said shaft,

a cylinder block being positioned about said shaft, said blockhaving aplurality of axially extending splines said piston pump including aswash complementally positioned to the splines on said shaft forrotation of said cylinder block with said shaft, plurality ofreciprocable pistons positioned within said axial cylinder bores forreciprocation therein, said pistons each having a ball portion at oneend, said pistons being positioned with said ball end extendingoutwardly from said cylinder bores toward the second end of said shaft,1

plate pivotable about the right end of said shaft, a Y plurality oftrunnion bearings mounted within said housing and supporting said swashplate for pivotal movement about said shaft, said swash plate having agenerally cylindrical opening facing said pistons, thrust plate beinggenerally annular in shape and being positioned within said cylindricalopening in said swash plate, said thrust plate having a generally flat,surface facing said pistons, Y slipper positioned arcuately about saidshaftan having a first and second end, said first end having meansproviding socket openings therein, said second end comprising agenerally flat surface being generally complemental to the flat surfaceof said thrust plate and being adapted for sliding movement on saidthrust plate, said ball ends of said pistons being fitted within saidsockets of said slipper,

slipper retainer guide positioned about a portion of the second end ofsaid cylinder block, said slipper retainer guide being splined to saidshaft for rotation therewith,

1 1 a slipper retainer positioned about said slipper and being adaptedto maintain said slipper in bearing contact with said thrust plate,

first and second valve plates being positioned at the first end of saidcylinder block between said housing and said cylinder block, said firstvalve plate comprising a stationary housing plate, said second valveplate being a cylinder block plate for rotation therewith, said valveplates having intermediate abutting relatively rotating flat faceportions, said valve plates being positioned adjacent said firstanti-friction bear ings and being in fluid communication therewith, theimprovement comprising:

means providing said shaft with an axial passageway extending throughsaid shaft between said first and second bearings,

means providing said shift with first radial passageways positionedadjacent said first bearings and extending communicatively between saidaxial shaft passageway into said first bearings;

means providing each of said valve plates with a plurality of radiallyextending passageways adjacent said face portions communicativelyconnecting said first anti-friction bearings and said fluid reservoir,

means providing splined fluid passageways extending axially between saidshaft splines and said complemental splines of said cylinder block;

means providing said shaft with second radially extending passagewaysextending communicatively between said axial shaft passageway and saidsplined fluid passageways at a point adjacent the valve plate end ofsaid splined passageways;

means providing said slipper retainer guide with a plurality of openingspositioned adjacent the second end of said cylinder block and being influid communication with said splined fluid passageways;

means providing said shaft with third radially extending passagewayspositioned at the second end of said axially extending passageway andextending communicatively therefrom to said second anti-frictionbearings;

means providing lubricant under pressure from said reservoir to saidaxially extending shaft passageway, where-by lubricant under pressureflows through said first, second and third radial passageways tolubricate said shaft bearings, flowing radially outwardly in saidaxially extending valve grooves to cool said valve plates and returningto said reservoir,

said lubricant also flowing through said second radially extending shaftpassageways to flow into said splined passageways, through said openingsprovided in said slipper retainer guide about said slipper and saidthrust plate and radially outwardly to lubricate said trunnion bearingsand returning to said reservoir.

4. The axial piston pump of claim 3 wherein said thrust plate ischamfered on an inner edge adjacent said cylinder block to encourage theflow of lubricating fluid radially outwardly over said chamfered edgeabout said slipper and trunnion bearings.

5. The axial piston pump of claim 3 wherein said means providing splinedfluid passageways extending axially in said splined area of said shaftcomprises shaft splines which are undercut to permit a flow of fluidtherethrough.

6. In a hydraulic transmission including an axial piston pump, an axialpiston motor, conduit means communicatively connecting said pump andsaid motor, said pump and motor respectively having a rotating pump andmotor shaft, said shafts each havingan outer area having a plurality ofaxially extending splines thereon, pump and motor cylinder block beingsplined respectively to said pump and motor shaft splines for rotationof said cylinder blocks with said respective rotating shafts, inner pumpand motor anti-friction bearings supporting inner ends respectively ofsaid pump shaft and said motor shaft adjacent said conduit means, a pumpand a motor swash plate assembly axially spaced from said conduit means,outer pump and motor anti-friction bearings supporting outer endsrespectively of said pump shaft and said motor shaft, the improvementcomprising:

means providing a source of lubricating fluid under pressure;

means providing axially extending passageways in said pump and motorshaft in communication with said source of lubricating fluid;

pump and motor means each providing first, second and third radialpassageways connected communicatively to said pump and motor axiallyextending passageways, said pump and motor each having valve plateshaving radially extending passageways connected communicatively withsaid inner pump and motor anti-friction bearings, said first radiallyextending pump and motor passageways being in communication with saidpump and motor inner anti-friction bearings;

said second radially extending pump and motor passageways beingpositioned respectively at intermediate portions of said pump and motorshafts and leading communicatively from said axial pump and motorpassageways to said splined areas of said shaft at a positionimmediately adjacent the valve plate end of said splined area, meansproviding splined fluid passageways extending axially through said pumpand motor splined areas and connected communicatively respectively tosaid pump and motor swash plate assemblies; said third pump and motorradially extending passageways leading respectively communicatively fromsaid axially extending pump and motor passageways to said pump and motorouter antifriction bearings whereby lubricating fluid under pressure isdirected in predetermined proportions to said pump and motor bearings,splined areas of said pump and motor shafts, pump and motor valveplates, and pump and motor swash plate assemblies.

References Cited by the Examiner UNITED STATES PATENTS 7/1919 Ferris etal 103-162 11/ 1958 Cornelius 103-202 2/1961 Douglas 103-162 2/1964Firth et al 103-162 3/1964 Boyer a 103-162

1. IN AN AXIAL PISTON PUMP INCLUDING A HOUSING, A ROTATABLE DRIVE SHAFTEXTENDING THROUGH SAID HOUSING, SAID SHAFT HAVING FIRST AND SECOND ENDS,FIRST AND SECOND ANTIFRICTION BEARINGS SUPPORTING SAID SHAFT AT ITSFIRST AND SECOND ENDS RESPECTIVELY FOR ROTATION WITHIN SAID HOUSING,SAID SHAFT HAVING AN OUTER AREA HAVING A PLURALITY OF SPLINES EXTENDINGAXIALLY FROM A FIRST POINT AT AN INTERMEDIATE LOCATION ON SAID SHAFT ANDEXTENDING TO A SECOND POINT ADJACENT THE SECOND END OF SAID SHAFT, ACYLINDER BLOCK HAVING FIRST AND SECOND SPACED ENDS AND A PLURALITY OFAXIALLY EXTENDING SPLINES BEING COMPLEMENTALLY POSITIONED TO THE SPLINESON SAID SHAFT FOR ROTATION THEREWITH, SAID CYLINDER BLOCK HAVING APLURALITY OF AXIAL CYLINDER BORES, A PLURALITY OF PISTONS, EACH OF SAIDBORES HOUSING ONE OF SAID PISTONS FOR RECIPROCATION THEREIN, SAIDPISTONS EACH HAVING A BALL PORTION AT ONE END THEREOF, SAID BALLPORTIONS EXTENDING OUTWARDLY FROM SAID CYLINDER BORES TOWARD THE SECONDEND OF SAID SHAFT AND BEING FITTED WITHIN SOCKETED BEARING SURFACES, ASWASH PLATE ASSEMBLY BEING POSITIONED ABOUT THE SHAFT AT ITS SECOND ENDADJACENT THE SOCKETED BEARING SURFACES, SAID BEARING SURFACES BEINGPOSITIONED WITHIN SAID SWASH PLATE ASSEMBLY FOR CONTROLLED RECIPROCATIONOF SAID PISTONS, SAID HOUSING AND SAID CYLINDER BLOCK HAVINGRESPECTIVELY FIRST AND SECOND COMPLEMENTARY RELATIVELY ROTATABLE ANNULARVALVE PLATES TO CONTROL THE FLOW OF FLUID THROUGH SAID PISTON PUMP, SAIDVALVE PLATES BEING POSITIONED ADJACENT SAID FIRST ANTI-FRICTIONBEARINGS, SAID FIRST AND SECOND VALVE PLATES HAVING MATING RELATIVELYROTATING COMPLEMENTARY FACE PORTIONS THE IMPROVEMENT COMPRISING: MEANSPROVIDING AT LEAST ONE OF SAID FIRST AND SECOND VALVE PLATES WITHRADIALLY EXTENDING FLUID PASSAGEWAYS THERETHROUGH; SAID PASSAGEWAYSBEING ADJACENT SAID FACE PORTIONS, MEANS PROVIDING AN AXIAL SHAFTPASSAGEWAY EXTENDING AXIALLY THROUGH SAID ROTATING SHAFT BETWEEN SAIDFIRST AND SECOND ANTI-FRICTION BEARINGS; MEANS PROVIDING SAID SHAFT WITHFIRST RADIALLY EXTENDING PASSAGEWAYS POSITIONED ADJACENT SAID FIRSTANTIFRICTION BEARINGS AND EXTENDING COMMUNICATIVELY BETWEEN SAID AXIALSHAFT PASSAGEWAY AND SAID FIRST ANTIFRICTION BEARINGS; MEANSCOMMUNICATIVELY CONNECTING SAID FIRST ANTI-FRICTION BEARINGS AND SAIDRADIALLY EXTENDING VALVE PLATE PASSAGEWAYS; MEANS PROVIDING SAID SHAFTWITH SECOND RADIALLY EXTENDING PASSAGEWAYS POSITIONED ADJACENT SAIDSPLINED AREA OF SAID SHAFT BETWEEN SAID FIRST END OF SAID SHAFT AND SAIDINTERMEDIATE LOCATION ON SAID SHAFT, MEANS PROVIDING SPLINED FLUIDPASSAGEWAYS EXTENDING AXIALLY BETWEEN SAID SPLINED AREA OF SAID SHAFTAND SAID CYLINDER BLOCK, SAID SPLINED FLUID PASSAGEWAYS COMMUNICATIVELYCONNECTING SAID SECOND RADIALLY EXTENDING SHAFT PASSAGEWAYS WITH SAIDSWASH PLATE ASSEMBLY; AND MEANS PROVIDING A SOURCE OF LUBRICATING FLUIDUNDER PRESSURE TO SAID AXIALLY EXTENDING SHAFT PASSAGEWAY, WHEREBYLUBRICATING FLUID UNDER PRESSURE IS DIRECTED IN A LUBRICATING ANDCOOLING STREAM THROUGH SAID FIRST ANTIFRICTION BEARINGS, SAID VALVEPLATES, ABOUT THE SPLINED AREA OF SAID SHAFT AND SAID SWASH PLATEASSEMBLY.